1. Field of the Invention
The present invention relates to a data migration management apparatus and management method. A storage system provides a host computer with a redundant logical volume based on, for example, RAID (Redundant Array of Independent Disks). The system administrator and other users are able to move the location of the logical volume in accordance with, for example, the frequency with which the data is used (JP-A-2006-099748).
2. Description of the Related Art
In the prior art described in the above-mentioned patent document, a setup for a data migration (may also be shortened to migration hereinafter) is carried out based on information related to the volume load at a certain instant. However, the state of usage of the logical volume, for example, varies dynamically in accordance with the type of data stored in this logical volume, and the type of host application program using this logical volume. Therefore, it is not possible to determine a migration-targeted logical volume or a migration-destination array group (RAID Group) and carry out a suitable data migration based solely on the momentary load information at a certain point in time.
For example, even in the case of an array group for which the load is relatively high during the day, the load value may unexpectedly drop for a short period of time. In a case where a different logical volume is migrated into the array group based on this low load value that was measured by chance, the average load of the array group will further increase and response performance will drop.
Further, the prior art does not touch on the aspect of power consumption reduction at data migration execution. For example, migrating a logical volume that is frequently used during the daytime into an array group having another logical volume that is accessed frequently at night will result in the respective hard disk drives that configure this array group operating continuously day and night. Therefore, the time during which power can be shut off to the hard disk drives inside this array group is shortened and power consumption increases. The life of the hard disk drive is also affected.